Long-term influence of cropping systems, tillage methods, and N sources on nitrate leaching

Abstract

In a cryoboreal subhumid soil-climate of north-central Alberta, no NO3- were found under native forest vegetation. NO3-N accumulated below 0.9-m depth of agricultural ecosystems cultivated for as long as 64 yr ranged from 0 to 67 kg N ha-1. At Breton, fallow-wheat rotation plots receiving fertilizer N and manure contained eight times more NO3-N below 0.9 m depth than non-fertilized plots. NO3-N levels in an 8-yr legume-based rotation and in continuous-barley plots were similar but greater than in continuous-forage plots. Evidence of greater nitrate leaching under zero tillage than under conventional warrants further confirmation. -from Authors